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혼화재 치환이 초지연 콘크리트의 응결 및 공학적 특성에 미치는 영향
윤섭,김종,송용원,전충근,신동안,한천구 대한건축학회지회연합회 2005 대한건축학회지회연합회 학술발표대회논문집 Vol.1 No.1
According to the test, An increase of super-retarding-agent (SRA), which combined the SRA with admixture, delayed initial and final setting time. Interestingly control concrete incorporating only admixture also retarded setting time. In addition concrete, adding combination of the SRA and admixture simultaneously, exhibited considerable results, due to the absorbing, pozzolanic and potential hydraulicity reaction of the admixture. Overall, to secure initial setting time as control concrete does, particular coefficient value considering the properties of each materials, should be applied, before it is placed in the field construction.
배합요인이 자기충전 콘크리트의 워커빌리티 및 레올로지 파라미터에 미치는 영향 분석
윤섭,한민철,Yoon, Seob,Han, Min-Cheol 한국건축시공학회 2018 한국건축시공학회지 Vol.18 No.3
본 연구에서는 SCC의 높은 민감성으로 인한 품질관리에 어려움을 극복하고자 굵은 골재의 부피, 잔골재의 종류, 단위수량, 공기량, 증점제 사용량 변화 등과 같은 다양한 배합요인이 SCC 특성에 미치는 영향을 분석하여 SCC의 초기물성을 정량적으로 판단할 수 있는 기초자료를 제공하고자 하였다. 실험결과, 항복응력은 굵은 골재 용적율이 증가할수록 낮아졌고 증점제 사용량이 증가할수록 증가하는 것으로 나타났다. 그러나 단위수량, 잔골재 종류 변화, 공기량 증감에 따른 항복응력값의 변화는 없는 것으로 나타났다. 배합요인에 따른 소성 점도는 항복응력과 비슷한 경향을 나타냈다. 또한 항복응력과 슬럼프 플로, $T_{50}$, V-lot와의 상관성 분석결과, 상관관계가 없었고 소성 점도와 $T_{50}$, V-lot와의 상관성은 매우 밀접한 관계가 있는 것으로 나타났는데, 특히, $T_{50}$ 및 V-lot 시간이 줄어들수록 소성 점도도 낮아지는 것을 알 수 있었다. The objective of the paper is to investigate the effect of mix designing factors on the workability and rheological parameters of self compacting concrete in order to facilitate the difficulties of quality control of high sensitivity of SCC. Mix proportions of SCC were prepared with various conditions of coarse, and fine aggregate, and unit water content, and the SCC mixtures were tested on workability, rheological properties to provide basic data for quantitative evaluation. Test results indicated that the yield stress of SCC decreased with increasing the coarse aggregate volume ratio, and increased with increasing the amount of VMA. However, unit water content, fine aggregate type, and air content didn't affect the yield stress value. The plastic viscosity according to the mixing factors showed a similar tendency to the yield stress. In addition, there was no correlation between yield stress and workability (flow, T50, V-lot). However, there was closely correlation among plastic viscosity and T50 and V-lot. Especially, T50 and V-lot time decreased with decreasing plastic viscosity.
유공 유리분말이 자기충전 콘크리트의 특성에 미치는 영향
윤섭,한민철 한국건축시공학회 2018 한국건축시공학회지 Vol.18 No.2
In this study, compacting, passing performance, segregation resistance and rheological properties were tested to improvethe stability of fresh concrete in the production and construction of self-compacting concrete (SCC) using hollow glasspowder(GB). As a result, T50 reaching time was shortened up to amount of GB 2.0kg/m3. The compacting according tothe amount of GB was improved by ball bearing effect of GB. However, T50 reaching time was slightly increased at4.0kg/m3. In the case of passing performance, the result showed that plain was Class 1, GB 0.5~2.0kg/m3 was Class 0,GB 4.0kg/m3 was Class 1. Therefore, the passing performance was improved with ‘No blocking’ up to amount of GB2.0kg/m3. Passing performance Block step (PJ) number by J-ring method was also best at GB 1.0kg/m3. In the case ofsegregation resistance according to the amount of GB, dynamic segregation resistance was increased compared to plainregardless of the amount of GB. And static segregation resistance showed 2.5% of segregation rate at GB 1.0kg/m3. Therefore, it was greatly improved compared to plain (12.5%). In the case of rheology property according to the amountof GB, plastic consistency by increasing of GB content didn't show big difference. However, yield stress by increasing ofGB content was decreased with GB 1.0kg/m3. In conclusion, GB 1.0kg/m3 was effective for improvement of compacting,passing performance and yield stress. Also, it will be useful for stability of SCC by improving segregation. 본 연구는 자기충전 콘크리트의 생산 및 시공 시 굳지 않은상태의 안정성을 향상시킬 목적으로 유공 유리분말(GB)를혼입한 자기충전 콘크리트에 대하여 충전성, 통과성, 재료분리 저항성 및 레올로지 특성을 평가하였다. 실험결과, GB혼입량에 따른 충전성은 GB의 볼베어링 효과로 인해 GB2.0kg/m3까지 T50 도달시간이 Plain에 비하여 단축되어 충전성이 개선되는 것으로 나타났다. 단, GB 4.0kg/m3에서는 오히려 약간 증가되었다. 통과성의 경우에는 Plain 1등급, GB 0.5~2.0kg/m3 0등급, GB 4.0kg/m3 1등급으로GB 혼입량 2.0kg/m3까지 ‘보이는 차단 없음’으로 통과성이개선되었다. J-ring에 의한 통과성 Block step(PJ) 값도GB 1.0kg/m3에서 가장 우수한 통과성을 나타내었다. GB혼입에 따른 재료분리 저항성은 동적 재료분리 저항성은Plain 보다 GB을 사용하게 되면 그 혼입량에 상관없이 동적재료분리 저항성이 증가하였다. 정적 재료분리 저항성은 GB1.0kg/m3에서 재료분리도 2.5%를 나타내어 Plain(12.5%)대비 크게 개선되었다. GB 혼입에 따른 레올로지 특성은GB 혼입량 증가에 따른 소성 점도는 큰 차이가 발생하지않았으나 항복응력은 1.0kg/m3까지 낮아졌다. 이상을 종합하면, GB를 1.0kg/m3 사용하게 되면 자기충전 콘크리트의 충전성, 통과성, 항복응력 개선에 효과적인 것으로 나타났다. 또한 재료분리 저항성을 증가시켜 자기충전 콘크리트의안정성에 도움이 될 것으로 판단된다.
구조체 콘크리트의 건조수축 균열 저감에 관한 Mock-up 실험
윤섭,한천구,한민철,송승헌 대한건축학회 2006 大韓建築學會論文集 : 構造系 Vol.22 No.11
In this paper, tests were carried out using mock-up concrete structures to verify the shrinkage reducing method by applying flowing concrete method along with expansive additive(EA) and shrinkage reducing admixture(SRA). Optimal addition ratio of EX and SRA were determined initially through laboratory tests. Based on laboratory test 4 different wall and slab shape mock-up structures were fabricated reflecting mixture and execution condition. D structure, which applied flowing concrete method along with EX and SRA, resulted in shortening of setting time compared to that of A structure(conventional concrete), while bleeding decreased slightly and compressive strength relatively constant. For drying shrinkage, the effect of drying shrinkage reduction is in order of D>C(combination of EX and SRA)>B(flowing concrete method)>A(conventional concrete). For the effect of member thickness and position, thin section in cross section and outer part had larger drying shrinkage. It is clarified from the results of present paper that the application of flowing concrete method along with EX and SRA makes it possible to secure the stability against drying shrinkage.
글루콘산계 지연제의 종류 및 혼입률 변화에 따른 시멘트 모르터의 응결 및 강도특성
윤섭,황인성,백병훈,한천구 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)
In this paper, fundamental engineering properties of cement mortar with gluconic based super retarding admixture(GSRA) type and content are discussed. For fresh mortar properties, flow of cement mortar exhibited an increase tendency with an increase in GSRA content. Remarkable flow loss was not observed at GSRA A with an elapse of age. For setting properties, presence of GSRA affected the setting time retarding. The effect of GSRA type on setting time retarding is in order for A, B, C. This is due to the gap of consistency. Compressive strength of cement mortar with GSRA is higher than that with plain mortar after 28days since final set.
윤섭 ( Yoon Seob ),송승헌 ( Song Seung Heon ),한민철 ( Han Min Cheol ),김경환 ( Kim Gyeong Hwan ),정용희 ( Jong Young Hee ),한천구 ( Han Cheon-goo ) 한국구조물진단유지관리공학회 2005 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.9 No.1
This study reported mock-up test on investigation of reducing shrinkage concrete. Test results show that concrete incorporating expansive additive(EA), shrinkage reducing agent(SRA) and flowing method(FM) was not affected fluidity, bleeding, setting time and compressive strength. For the properties of drying shrinkage, Number ’one’ position of specimen, which is small area, exhibited high drying shrinkage, while specimen ’D’ incorporating EA, SRA, and FM at the same time, presented favorable effect, which reduce 30 to 40 % of drying shrinkage, compared with plain concrete.
윤섭(Yoon Seob),송승헌(Song Seung Hean),한민철(Han Min Cheol),김경환(Kim Gyeong Hwan),정용희(Jong Young Hee),한천구(Han Chean-Goo) 한국구조물진단유지관리학회 2005 한국구조물진단학회 학술발표회논문집 Vol.- No.-
This study reported mock-up test on investigation of reducing shrinkage concrete. Test results show that concrete incorporating expansive additive(EA). shrinkage reducing agent(SRA) and flowing method(FM) was not affected fluidity, bleeding, setting time and compressive strength. For the properties of drying shrinkage, Number 'one' position of specimen, which is small area, exhibited high drying shrinkage, while specimen 'D' incorporating EA, SRA, and FM at the same time, presented favorable effect, which reduce 30 to 40% of drying shrinkage, compared with plain concrete.
조기강도발현형 AE감수제를 사용한 콘크리트의 초기강도발현 및 내구특성
윤섭(Yoon sob),황인성(Hwang Yin Seong),김규동(Kim Gyu Dong),이승훈(Lee Seung Hoon),한천구(Han Cheon-Goo) 한국구조물진단유지관리학회 2003 한국구조물진단학회 학술발표회논문집 Vol.- No.-
This study discuss early strength development and durability of concrete, which AE water reducing agent of early strength type is used, with the replacing method of fly ash and blast furnace slag powder. According to the results, setting time is shortened in comparison with normal AE water reducing agent. compressive strength gains 5MPa before 16 hours, and as for the replacing method of mineral admixture, it shows higher value in order of replacement for fine aggregate, combination and replacement for cement. The rebound value of P type schmidt hammer shows a similar tendency to compressive strength. The rebound value, which compressive strength is more than 5MPa, shows 18, so it is thought that the use of P type schmidt hammer enables quality control related to estimation of compressive strength. AE water reducing agent of early strength type does not differ from normal AE water reducing agent in terms of durability such as length change ratio and neutralization, so there is no quality variation related to durability. As for replacement of mineral admixture, length change ratio and neutralization decreases in order of fine aggregate, combination and replacement for cement.